Improvement and validation the method using dispersive liquid-liquid microextraction with in situ derivatization followed by gas chromatography-mass spectrometry for determination of tricyclic antidepressants in human urine samples.

A simple, rapid and sensitive method termed dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-mass spectrometry (GC/MS) was developed for the determination of tricyclic antidepressants (TCAs) in human urine sample. An appropriate mixture of methanol (disperser solvent), carbon tetrachloride (extraction solvent), and acetic anhydride (derivatization reagent) was injected rapidly into human urine sample. After extraction, the sedimented phase was analyzed by GC/MS. The calibration curves obtained with human urine were linear with a correlation coefficient of over 0.99 in the range of 2.0/5.0-100 ng mL(-1). Under the optimum conditions (carbon tetrachloride: 10 µL, methanol: 150 µL), the detection limits and the quantification limits of the tricyclic antidepressants were 0.5-2.0 ng mL(-1) and 2.0-5.0 ng mL(-1), respectively. The average recoveries of TCAs were 88.2-104.3%. Moreover, the inter- and intra-day precision and accuracy was acceptable at all concentrations. The results showed that DLLME is applicable to the determination of trace amounts of TCAs in human urine sample.

Urine sample preparation of tricyclic antidepressants by means of a supported liquid membrane technique for high-performance liquid chromatographic analysis.

Supported liquid membrane (SLM) technique for sample work-up and enrichment was used for determination of tricyclic antidepressant drugs in urine by high-performance liquid chromatography (HPLC) with UV detection. The studied antidepressant drugs were amitriptyline, opipramol, noxiptyline and additionally diethazine was used as possible internal standard. Alkaline phosphoric buffer with urine sample, as the donor solution, was passed over the liquid membrane into which investigated substances were extracted. On the other side of the membrane, analyzed compounds were trapped due to creating non-extractable form in acidic acceptor solution. Enriched and cleaned up drugs were then injected into a HPLC system with ultraviolet detection to analyze of their concentration in acceptor solution. Optimum extraction efficiency was determined by changing acceptor and donor solutions pH, application of different flow rates of donor solution and by using different solvents in the membrane. Also, donor solution volume, extraction time and concentration of analytes were varied to check the linearity of extraction process. The highest extraction efficiency: 43% for opipramol, 56% for noxiptyline, 43% for amitriptyline and 42% for diethazine (R.S.D. values were <6% and n=3) was achieved when 0.05 M phosphate buffer pH 4.0 and 9.5 were used as donor and acceptor solutions, respectively, n-undecane with 5% tri-n-octylphosphine oxide (TOPO) was used as liquid membrane. Limit of quantification (LOQ) for tricyclic antidepressants after enrichment of 100ml of urine sample was about 1 ng/ml.

Metabolism of amineptine in rat, dog and man.

After oral administration of amineptine (7-[(10-11)-dihydro-5H-dibenzo(a,d)cycloheptane-5yl] amino heptanoic acid), an original tricyclic antidepressant, seven metabolites were isolated from urine and plasma of rat, dog and man. The metabolic pathways were similar for the three species studied. The two major pathways consisted of the beta-oxidation of the heptanoic side chain leading to pentanoic (first step) and propanoic (second step) side chain metabolites and the hydroxylation of the dibenzocycloheptyl ring on carbon atom 10 (C10) causing the formation of two diastereoisomers. Lactamization by internal dehydration of beta-oxidized metabolites appeared to be a minor route of biotransformation. Conjugation reactions were of minor importance in the rat, in contrast to findings for dog and man. Urinary elimination was the major route of excretion in man while in dog and in rat faecal excretion was predominant.

Disposition and metabolism of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cyclohepten-5,10-imine in rats, dogs, and monkeys.

The disposition and metabolism of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), a new agent with potent anticonvulsant, central sympathomimetic, and apparent anxiolytic properties, was studied in rats, dogs, and rhesus monkeys. [3H]benzene-MK-801 was administered orally at a dose of 1 mg/kg. MK-801 was measured in plasma by GLC using a nitrogen detector; the overall sensitivity of the method was 3 ng/ml. Radioactivity was excreted mainly in urine of dogs and monkeys but fecal excretion in rats was also extensive. The apparent plasma t1/2 of MK-801 in the rat and dog was approximately 1 hr. Maximal plasma levels of MK-801 in the rat, dog, and monkey were 46 (0.5 hr), 16 (0.25 hr), and 10 (2 hr) ng/ml, respectively. Radioactivity was extensively excreted in rat bile and was widely distributed among various tissues. Major metabolites of the drug in rat and dog urine were the 2- and 8-hydroxy analogs (rat) and the N-hydroxy derivative (dog).

Metabolism of cyclobenzaprine in the dog.

Ten metabolites of cyclobenzaprine, accounting for approximately 50% of the urinary radioactivity, were identified in the urine of dogs to which the labeled drug had been given orally. These included the 1,2-dihydrodiol, three phenolic derivatives, the N-oxide, the 10,11-epoxide, the 10,11-glycol, desmethylcyclobenzaprine, and the glucuronide conjugates of desmethylcyclobenzaprine and cyclobenzaprine. The metabolites were excreted in both the free and conjugated states. Unchanged cyclobenzaprine was present in only minor amounts.

GLC determination of cyclobenzaprine in plasma and urine.

A GLC determination of cyclobenzaprine in human plasma and urine is described. After extraction from alkalinized samples with heptane-isopentyl alcohol (97:3), the drug and internal standard were back-extracted into 0.1 N HCl and then reextracted into ether. Use of a lower homolog of the drug as an internal standard was effective in reducing variability. Drug concentrations as low as 25 ng/ml could be assayed with high precision. Plasma levels in humans given 40 mg po or iv ranged from 5 to 51 ng/ml; little unchanged cyclobenzaprine was present in the urine. The N-desmethyl analog of the drug was detected as a metabolite in urine.

Identification of 10, 11-epoxide and other cyclobenzaprine metabolites isolated from rat urine.

Cyclobenzaprine (40 mg/kg ip) was administered to rats, and six urinary metabolites of this drug were identified. They were the 10, 11-epoxide, the N -oxide, the desmethyl derivative, the hydroxylated and desmethylhydroxylated compounds, and the N-oxide hydroxylated at the 10- or 11-position. Mass spectrometric analysis confirmed their structures.